[llvm] [RISCV][GlobalISel] Select G_PTR_ADD (PR #67605)
via llvm-commits
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Wed Sep 27 13:55:00 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-globalisel
<details>
<summary>Changes</summary>
We lower G_PTR_ADD to G_ADD before selection. We choose to do this here and not post-legalization because G_PTR_ADD can still be combined with other instructions during selection.
---
Full diff: https://github.com/llvm/llvm-project/pull/67605.diff
3 Files Affected:
- (modified) llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp (+51-2)
- (added) llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/ptradd-rv32.mir (+50)
- (added) llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/ptradd-rv64.mir (+50)
``````````diff
diff --git a/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp b/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
index 2e690a3624edcb3..301a9ce0c3b813a 100644
--- a/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
+++ b/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
@@ -45,6 +45,16 @@ class RISCVInstructionSelector : public InstructionSelector {
getRegClassForTypeOnBank(LLT Ty, const RegisterBank &RB) const;
bool selectImpl(MachineInstr &I, CodeGenCoverage &CoverageInfo) const;
+
+ // A lowering phase that runs before any selection attempts.
+ // Returns true if the instruction was modified.
+ bool preISelLower(MachineInstr &MI, MachineIRBuilder &MIB,
+ MachineRegisterInfo &MRI);
+
+ bool replacePtrWithInt(MachineOperand &Op, MachineIRBuilder &MIB,
+ MachineRegisterInfo &MRI);
+
+ // Custom selection methods
bool selectCopy(MachineInstr &MI, MachineRegisterInfo &MRI) const;
bool selectConstant(MachineInstr &MI, MachineIRBuilder &MIB,
MachineRegisterInfo &MRI) const;
@@ -130,12 +140,14 @@ bool RISCVInstructionSelector::earlySelectShift(
}
bool RISCVInstructionSelector::select(MachineInstr &MI) {
- unsigned Opc = MI.getOpcode();
MachineBasicBlock &MBB = *MI.getParent();
MachineFunction &MF = *MBB.getParent();
MachineRegisterInfo &MRI = MF.getRegInfo();
MachineIRBuilder MIB(MI);
+ preISelLower(MI, MIB, MRI);
+ const unsigned Opc = MI.getOpcode();
+
if (!isPreISelGenericOpcode(Opc) || Opc == TargetOpcode::G_PHI) {
if (Opc == TargetOpcode::PHI || Opc == TargetOpcode::G_PHI) {
const Register DefReg = MI.getOperand(0).getReg();
@@ -225,9 +237,13 @@ bool RISCVInstructionSelector::select(MachineInstr &MI) {
switch (Opc) {
case TargetOpcode::G_ANYEXT:
- case TargetOpcode::G_TRUNC:
+ case TargetOpcode::G_PTRTOINT:
+ case TargetOpcode::G_TRUNC: {
MI.setDesc(TII.get(TargetOpcode::COPY));
+ bool Selected = selectCopy(MI, MRI);
+ assert(Selected && "Could not select copy!");
return true;
+ }
case TargetOpcode::G_CONSTANT:
return selectConstant(MI, MIB, MRI);
case TargetOpcode::G_BRCOND: {
@@ -245,6 +261,39 @@ bool RISCVInstructionSelector::select(MachineInstr &MI) {
}
}
+bool RISCVInstructionSelector::replacePtrWithInt(MachineOperand &Op,
+ MachineIRBuilder &MIB,
+ MachineRegisterInfo &MRI) {
+ assert(Op.isReg() && "Operand is not a register!");
+ Register PtrReg = Op.getReg();
+ assert(MRI.getType(PtrReg).isPointer() && "Operand is not a pointer!");
+
+ const LLT XLenLLT = LLT::scalar(STI.getXLen());
+ auto PtrToInt = MIB.buildPtrToInt(XLenLLT, PtrReg);
+ MRI.setRegBank(PtrToInt.getReg(0), RBI.getRegBank(RISCV::GPRRegBankID));
+ MRI.setType(PtrReg, XLenLLT);
+ Op.setReg(PtrToInt.getReg(0));
+ return select(*PtrToInt);
+}
+
+bool RISCVInstructionSelector::preISelLower(MachineInstr &MI,
+ MachineIRBuilder &MIB,
+ MachineRegisterInfo &MRI) {
+ switch (MI.getOpcode()) {
+ case TargetOpcode::G_PTR_ADD: {
+ Register DstReg = MI.getOperand(0).getReg();
+ const LLT XLenLLT = LLT::scalar(STI.getXLen());
+
+ replacePtrWithInt(MI.getOperand(1), MIB, MRI);
+ MI.setDesc(TII.get(TargetOpcode::G_ADD));
+ MRI.setType(DstReg, XLenLLT);
+ return true;
+ }
+ default:
+ return false;
+ }
+}
+
void RISCVInstructionSelector::renderNegImm(MachineInstrBuilder &MIB,
const MachineInstr &MI,
int OpIdx) const {
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/ptradd-rv32.mir b/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/ptradd-rv32.mir
new file mode 100644
index 000000000000000..bc0395685b40e9e
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/ptradd-rv32.mir
@@ -0,0 +1,50 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -march=riscv32 -run-pass=instruction-select -simplify-mir \
+# RUN: -verify-machineinstrs %s -o - | FileCheck %s
+---
+name: add_i32
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+body: |
+ bb.0.entry:
+ liveins: $x10, $x11
+
+ ; CHECK-LABEL: name: add_i32
+ ; CHECK: liveins: $x10, $x11
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x10
+ ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr = COPY $x11
+ ; CHECK-NEXT: [[ADD:%[0-9]+]]:gpr = ADD [[COPY]], [[COPY1]]
+ ; CHECK-NEXT: $x10 = COPY [[ADD]]
+ ; CHECK-NEXT: PseudoRET implicit $x10
+ %0:gprb(p0) = COPY $x10
+ %1:gprb(s32) = COPY $x11
+ %2:gprb(p0) = G_PTR_ADD %0, %1
+ $x10 = COPY %2(p0)
+ PseudoRET implicit $x10
+
+...
+---
+name: addi_i32
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+body: |
+ bb.0.entry:
+ liveins: $x10, $x11
+
+ ; CHECK-LABEL: name: addi_i32
+ ; CHECK: liveins: $x10, $x11
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x10
+ ; CHECK-NEXT: [[ADDI:%[0-9]+]]:gpr = ADDI [[COPY]], 20
+ ; CHECK-NEXT: $x10 = COPY [[ADDI]]
+ ; CHECK-NEXT: PseudoRET implicit $x10
+ %0:gprb(p0) = COPY $x10
+ %1:gprb(s32) = G_CONSTANT i32 20
+ %2:gprb(p0) = G_PTR_ADD %0, %1
+ $x10 = COPY %2(p0)
+ PseudoRET implicit $x10
+
+...
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/ptradd-rv64.mir b/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/ptradd-rv64.mir
new file mode 100644
index 000000000000000..d024a7c659878de
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/instruction-select/ptradd-rv64.mir
@@ -0,0 +1,50 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -march=riscv64 -run-pass=instruction-select -simplify-mir \
+# RUN: -verify-machineinstrs %s -o - | FileCheck %s
+---
+name: add_i64
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+body: |
+ bb.0.entry:
+ liveins: $x10, $x11
+
+ ; CHECK-LABEL: name: add_i64
+ ; CHECK: liveins: $x10, $x11
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x10
+ ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr = COPY $x11
+ ; CHECK-NEXT: [[ADD:%[0-9]+]]:gpr = ADD [[COPY]], [[COPY1]]
+ ; CHECK-NEXT: $x10 = COPY [[ADD]]
+ ; CHECK-NEXT: PseudoRET implicit $x10
+ %0:gprb(p0) = COPY $x10
+ %1:gprb(s64) = COPY $x11
+ %2:gprb(p0) = G_PTR_ADD %0, %1
+ $x10 = COPY %2(p0)
+ PseudoRET implicit $x10
+
+...
+---
+name: addi_i64
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+body: |
+ bb.0.entry:
+ liveins: $x10, $x11
+
+ ; CHECK-LABEL: name: addi_i64
+ ; CHECK: liveins: $x10, $x11
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x10
+ ; CHECK-NEXT: [[ADDI:%[0-9]+]]:gpr = ADDI [[COPY]], 20
+ ; CHECK-NEXT: $x10 = COPY [[ADDI]]
+ ; CHECK-NEXT: PseudoRET implicit $x10
+ %0:gprb(p0) = COPY $x10
+ %1:gprb(s64) = G_CONSTANT i64 20
+ %2:gprb(p0) = G_PTR_ADD %0, %1
+ $x10 = COPY %2(p0)
+ PseudoRET implicit $x10
+
+...
``````````
</details>
https://github.com/llvm/llvm-project/pull/67605
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